1. Technical Field
The present invention relates to a liquid container that contains therein a liquid, such as ink or the like, and supplies the liquid to an apparatus on which the liquid container is mounted.
2. Related Art
As a liquid container, an ink cartridge that is used in an ink jet printer is exemplified. In an ink cartridge for an ink jet printer, an ink containing chamber that contains therein ink to be supplied to a printing head is formed in a container main body. When used, the ink cartridge is detachably fitted into and mounted on a cartridge mounting portion of the ink jet printer. Then, ink contained in the ink containing chamber is supplied to the printing head, and ink is ejected from nozzles at a target position of a medium to be printed, such as a paper or the like, according to driving of the printing head on the basis of print data transmitted from a host computer.
There have been many atmosphere opening type ink cartridges that are mounted on an ink jet printer. Such an atmosphere opening type ink cartridge includes, in a containing main body, which is detachably mounted on a cartridge mounting portion of a printer, an ink containing chamber that contains ink therein, an ink supply port that is provided to communicate with the ink containing chamber and is connected to an ink receiving portion of the cartridge mounting portion, and an atmosphere opening flow passage that communicates the ink containing chamber with the outside and introduces external air into the ink containing chamber as ink in the ink containing chamber is consumed.
Further, there is suggested an ink cartridge that has an air chamber provided at a lower position outside an ink containing chamber, and air-liquid separation films communicating the air chamber and the ink containing chamber by an exclusive-use air introduction, path. The air-liquid separation films having a relatively large area are provided on both side surfaces of the air chamber so as to transmit air but block the liquid (for example, see Patent Document 1).
Patent Document 1: JP-A-2004-209847
In general, in the ink cartridge, there are many cases where, when the liquid supply port is formed at the bottom surface, the atmosphere opening port is formed at the top surface. If the atmosphere opening port is formed at the top surface, ink rarely leaks from the ink cartridge.
However, when the openings are formed at the top and bottom surfaces of the ink cartridge, a mold for forming the cartridge may be complicated, and a variation in molding accuracy of the ink cartridge may occur, which may cause an increase in manufacturing cost. Accordingly, there is suggested a method that provides the atmosphere opening port may be formed at a place other than the top surface, for example, at the bottom surface. However, if the atmosphere opening port is provided at the bottom surface, ink leakage may easily occur.
In addition, in the atmosphere opening type ink cartridge, the atmosphere opening port is generally sealed by a sealing film or the like so as to prevent ink evaporation or leakage in the ink containing chamber before the ink cartridge is used. Then, the sealing film is removed before the ink cartridge is mounted on the ink jet printer, and the ink cartridge is used in a state where the internal ink containing chamber communicates with the outside through the atmosphere opening port.
Here, if the ink cartridge is mounted on the ink jet printer with the atmosphere opening port sealed, ink cannot be supplied from the ink cartridge to the ink jet printer, and a trouble may occur in the printing head. Accordingly, in an ink jet printer, when the ink cartridge is mounted on the ink jet printer, the sealing film is torn off by an ink cartridge cover, such that the atmosphere opening port communicates with the outside even though the sealing film is not removed (for example, see Patent Documents 2 and 3).
Patent Document 2: JP-A-2002-36580
Patent Document 3: JP-A-11-129492
However, in the ink cartridge disclosed in Patent Document 2, since the sealing film is torn off by the ink cartridge cover, an operation force of a fixing lever for fixing the cover becomes large, and unfavorable operationality is obtained.
Further, after an ink supply needle of the ink jet printer is inserted into the ink supply port of the ink cartridge and an ink path communicates the ink cartridge and the ink jet printer with each other, the sealing film is torn off, and the ink cartridge is opened to the atmosphere.
Meanwhile, when a large amount of air is dissolved in ink to be supplied to a recording head, air bubbles may occur in the recording head due to a small change in pressure and printing quality may be degraded. For this reason, an ink cartridge is preferably packed in a compressed pack that is compressed and sealed to have an internal air pressure equal to or less than an atmospheric pressure. The internal air pressure of the ink cartridge is lowered to a regular value or less by a negative absorption force of the compressed pack, and the amount of air dissolved in ink is suppressed to a regular value or less. However, if the ink cartridge is mounted on the ink jet printer in a state where the internal pressure of the ink cartridge is lower than the pressure of the ink flow passage of the ink jet printer, ink may be reversely absorbed from the ink jet printer toward the ink cartridge. In this case, as occasion demands, air bubbles that have an adverse effect on printing quality may occur in the head, and thus there is much room for improvement.